1. Field of the Invention
This invention relates to the field of portable "on location" steam carpet cleaning and particularly to a method and apparatus for cleaning a carpet on location while also retarding the rate of resoiling for the cleaned carpet.
2. Description of the Prior Art
Carpet-cleaning methods and apparatuses have been known and practiced for many years. In this regard, the following represents only a small sample of the many patents issued in this area.
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 1,240,799 Gray 9/18/17 2,572,142 Hartenbach 10/23/51 2,731,659 Coplen 1/24/56 2,789,031 Caronia 4/16/57 3,262,146 Hays 7/26/66 3,540,072 Wolter et al. 11/17/70 3,812,552 Blackmon 5/28/74 3,815,169 Mooring 6/11/74 3,919,729 Cannan 11/18/75 ______________________________________
At first, carpets were removed from their location in the home or office and taken to plants where the cleaning process was accomplished. In such cleaning techniques, the carpets were generally tacked or nailed to a frame or border, scrubbed and rinsed thoroughly using various detergent solutions and buckets of clean water, and then stacked or hung up in a portion of the plant and allowed to dry. The dry, and hopefully unshrunken, carpets were then returned to their original locations until further cleaning was required.
In recent years, portable steam cleaning methods and apparatuses have been developed which permit the cleaning of carpets "on location," i.e., in the home, office or whatever, without having to remove the carpets and send them to an in-plant operation. For the purposes of this application, and the specification and claims contained herein, any reference to cleaning or otherwise handling a carpet "on location" shall be meant to indicate a method or portable apparatus capable of cleaning or otherwise handling a carpet at its original location, i.e., in the home or office, and without removing the carpet to a separate cleaning facility.
These steam cleaning operations generally involve the use of a cleaning head which has at least one spray nozzle that operates to spray a dilute, hot detergent solution having a pH registering in the area of 10 or above into the surface of the carpet. A vacuum system often also incorporated in the head design then operates to remove the sprayed detergent solution and loosened dirt from the carpet and to carry them to a waste storage tank for later disposal.
The problem with such steam cleaning operations is the strong alkaline residue left on the carpets after cleaning. Upon checking the alkalinity of the carpet fiber immediately following such a cleaning, it is found that the carpet registers a pH just as high as the alkaline detergent used in the method. Such high alkalinity remains with the carpet fiber for a long time and greatly accelerates and increases the rate of resoiling for the particular carpet. This is true because dirt is generally acidic in character and will therefore be attracted to the alkaline residue left on the carpet fiber after cleaning. The "bottom line" is thus that the more an individual carpet is cleaned using such a method, the sooner the carpet will have to be cleaned again. The problems and inadequacies with such a situation are obvious.
Acid solutions have also been known and used in the art of carpet cleaning over the years. Specifically, acid solutions generally composed of acetic acid were often used in in-plant cleaning operations to stop the browning of some lignt-colored carpets and to treat the fringes of oriental rugs. After washing with a detergent solution, and with the carpet still nailed down as above described, workers would apply the acid solution, possibly containing acetic acid, sodium biflouride, ammonium biflouride or others, to the light carpet or oriental fringe using rubber gloves and sponges or brushes. After working the acid solution into the carpet, it was then rinsed thoroughly using ample clean water, as previously described, and set aside to dry before returning it to the customer.
Another use of acid solutions in carpet-cleaning operations, of which applicant is aware, was the attempted combination of an acid salt with an alkaline cleaning agent in a one-step cleaning method. Such attempt was totally unsuccessful in that the cleaning agent was neutralized by the free acid released in solution and the free acid attacked and ruined the pumps and other apparatus used in the operation.